Sudden Airlock activity after repitch

Oh, I can tell I am about to get yelled at

So we brewed a batch of the double IPA from keg cowboy on Saturday, my third. From what I can tell, nothing was amiss, cooled wort to 80, added cold water, sitting around 70, oxygenate beer, pitch rehydrated yeast, and wait.

24 hours goes by, and nothing... I have a room in the house that sits at 66 degrees on the dot. I change from a 3 piece to an S because the 3 piece seems like it is sucking air in (odd). On doing so, I peek inside, no krausen, just the hops that went in with it.

What I can do, though, at that point is hear what sounds like soap suds. I take this as a good sign, and resume daily life.

60 hours in, still no airlock activity, still no krausen. Buddy advises to repitch, so I do, same process, sterilize water by boiling, cool to 75 degrees, wait a bit, oxygenate beer (this seemed logical if I had killed previous yeast), and pitch. This time, before oxygenating, I shook the bucket, and it foamed like it had been waiting all these years to foam, foam foam.

WTF? Was the yeast waiting for me to shake the bucket? Note that this was a 2" layer of hops on top, with no activity at all. I would have taken a gravity reading but I don't have a tube tall enough yet (its ordered). At that point, bucket was already shaken, so I proceeded with oxygen and pitch.

Now for the weird part. I seal it up, stick the airlock on it, and immediate activity, like 1 per second activity. I suspect that is the oxygen coming out of solution?

I have looked around, and am newb enough to get nervous when things aren't the way they were. Any thoughts on this would be very appreciated.

Sounds like you had a bad seal initially man, the oxygenation a couple days in may have been bad, if the yeast were okay and you didn't know it that is..... Good luck and you'll prolly be fine....

I thought that, too, but the airlock was very responsive to a touch on the lid... I took a picture and waited 24 hours, and it did not move a bit (split 60/40, so not equalized).

Why do you have 2 inches of hops in there? That's probably why you couldn't see any krausen forming. If you're dry hopping, it should be done after fermentation is finished. Not during or before fermentation.

If this batch was already actively fermenting and if it was very far along, then the oxygenating you did the second time will likey oxidize the beer. When it's done, if it's indeed drinkable you might want to drink it quickly before off tastes start to develop from the oxygen.

That is getting to the root of the question, but how can there be fermentation without CO2 release?

My thoughts were, 1) I could have killed the yeast
2) For some reason, the yeast could have been sitting around not doing their job
-- But why? This kit, at the very end (end of boil, and 5 minutes left) you had 2 ounces of whole hops.
3) Everything was indeed fine, just no outward activity.

govya said:

That is getting to the root of the question, but how can there be fermentation without CO2 release?

My thoughts were, 1) I could have killed the yeast
2) For some reason, the yeast could have been sitting around not doing their job
-- But why? This kit, at the very end (end of boil, and 5 minutes left) you had 2 ounces of whole hops.
3) Everything was indeed fine, just no outward activity.

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1) I seriously doubt you killed the yeast unless you rehydrated at a temp that was too high.
2) It's not uncommon for yeast to be working without much visual signs. Airlocks off-gasing co2 is not indication of fermentation. All fermentations are different. The hops sitting on top were likely holding the co2 suspended in the liquid, and when you shook it the co2 was released. That's why it foamed up on you like you described.
Late kettle hop additions are not meant to stay in the wort. You're supposed to remove the hops before you put the wort in the fermenter. Fermentation will scrub any aroma or flavor from the hops, which is why you add dry hops after active fermentation has ended. Plus excessive hops that are in a beer for too long can create grassy/vegetal flavors.
3) As I mentioned before, visual signs of outward activity are not indication of fermentation. The only way to tell if beer is fermenting is to take a reading with your hydrometer to see if gravity is dropping.

Well, darn. At least I keg, so it will be drank pretty quickly. To clarify, those were my thoughts before, not after.

govya said:

Well, darn. At least I keg, so it will be drank pretty quickly. To clarify, those were my thoughts before, not after.

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For future reference, fermentation can take as long as 72 hours to show any progress. So, always give it that long before you even think about re-pitching or re-aerating. But don't do either of those things unless you check gravity first. I bet that 10 times out of 10 you won't need to re-pitch.

I'm sure your beer will still be good. It's all a learning experience.

How come you didn't take a gravity reading BEFORE you felt the need to repitch? Who did you KNOW you even needed to?

The only way to truly know what is going on in your fermenter is with your hydrometer. Like I said here in my blog, which I encourage you to read, Think evaluation before action you sure as HELL wouldn't want a doctor to start cutting on you unless he used the proper diagnostic instuments like x-rays first, right? You wouldn't want him to just take a look in your eyes briefly and say "I'm cutting into your chest first thing in the morning." You would want them to use the right diagnostic tools before the slice and dice, right? You'd cry malpractice, I would hope, if they didn't say they were sending you for an MRI and other things before going in....

The fact that your airlock is now bubbling should lead you to understand that an airlock is not a fermentation gauge it's a vent, a valve to release excess co2, or air in the fermenter...like, you know when you open the lid to do smething like take a grav reading, or pitch more yeast that you really didn't need, then snap the lid down on the fermenter, which pushes air into the headspace....which then OFF GASSES and bubbles the airlock as it exits.

Revvy said:

...you sure as HELL wouldn't want a doctor to start cutting on you unless he used the proper diagnostic instuments like x-rays first, right? You wouldn't want him to just take a look in your eyes briefly and say "I'm cutting into your chest first thing in the morning." You would want them to use the right diagnostic tools before the slice and dice, right? You'd cry malpractice, I would hope, if they didn't say they were sending you for an MRI and other things before going in....

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http://www.nbc.com/saturday-night-live/video/theodoric-of-york/n8661

I would have taken a gravity reading, had I a vessel to measure with. It's on the way.

The interest here was not to get a lecture, I want to understand the microbiology. If it is fermenting, which produces CO2, where did that CO2 go? Where was the expansion required? Can the hops store CO2 in solution at a greater density?

Your "theory" only works if your fermenter is a truly airtight environment, like a keg with an airlock that is welded in place, not even connect via a grommet, or where there is any chance of a leak, AND where the headspace is smaller than any co2 present.

Bubbling doesn't really mean anything other than the airlock is bubbling. And airlock is not a fermentation gauge, it's a vent to bleed off EXCESS gas, be it oxygen or EXCESS co2. It shouldn't be looked at as anything else, because an airlock can bubble or stop bubbling for whatever reasons, including a change in temperature (gas expands and contracts depending on ambient temps) changes in barometric pressure (You can have bubbling or suckback in the airlock, depending on pressure on the fermenter) whether or not a truck is going by on the street, the vacuum cleaner is running, or your dog is trying to have sex with the fermenter. Or co2 can get out around the lid of the bucket or the bung...it doesn't matter how the co2 gets out, just that it is.

For example a couple weekends ago if you lived in most of the United Sates, you experienced an unseasonable WARM UP over the weekend which could very easily result in gas expansion in your fermenter or secondary...In other parts of the states you had storms, which meant a change in barometric pressure...It was an active weekend weather wise. We had a TON of new brewers starting panic threads because suddenly beers that they had in secondary from their Christmas presents, that were doing nothing for weeks (like they should do in secondary,) suddenly their airlocks started bubbling. So they, having equated an airlock as a fermentation gauge and NOT a vent, suddenly started assuming that fermentation was happening (and in their nervous noobishness were just SO SURE that their beer was infected).....NOT for once even thinking in terms of airlocks merely being vents, and that gas expands when it is heated, and contracts when it is cooled. And that's going to cause airlock to bubble or stop....Just as much as fermentation.

That's why I tell folks to ignore what the airlock does or doesn't do. It really means little to the yeast.


And bubbles don't coordinate with anything concrete withing the fermenter, "x bubbles/y minute" does NOT TRANSLATE to any numerical change in gravity....if an instructions says do something when bubbles do something per something, throw the instructions out.

Fermentation is not always dynamic, just because you can't see what's going on, doesn't mean nothing is going on. And just because your airlock starts up, and then slows down or stops in a few days, doesn't mean fermentation is over YET, it just means the excess co2 is not coming out of the airlock...not that the yeast is done.

The only way to know how your beer is doing is to take a hydrometer reading, if you're worried. But not until 72 hours have gone by. Then if you're still concerned, take one...then you'll know.

But don't try to discern what the yeast is doing by what the airlock is or isn't doing. All it is is a cheap piece of plastic, not a calibrated gauge of anything.

New brewers have a tendency to think they need to hover over their beers and try to fix something.....Next time before you try to fix something that may or may not need to be fixed, come here and look around first, OR start a thread...You will find that there will probably be a dozen threads just that day alone with EXACTLY the same situation you're in, with the solution. And the solution will be more than likely to relax, and wait, OR to ignore your senses and how you "think" it should behave, and use the proper tools.

Ok, got it, I'll do better next time.

I still want to know why the change happened, else I would not have posted.

It "foamed" because you added nucleation points to to the fermenter by adding billions of little particles into an environment with co2 and oxygen present in it.

Just like adding mentos into diet coke.

So the CO2 that is coming out now was in suspension in the fermenting liquid? And (may be reaching here), because it is a higher gravity beer, and I had crap on top that I (learned) that I am not supposed to have on top, the capability of the liquid to maintain a suspension of CO2 was greater than in, say, water?

Hey, at least I am not wishing you well about your surgery

Open a bottle of soda. Let it sit for a day. Now take the same soda and give it a good shake and you'll notice it might start fizzing again. That's what we call CO2 in suspension and is what Revvy is talking about.

govya said:

Can the hops store CO2 in solution at a greater density?

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I can't answer this question with any sort of certainty or track record, as I've never had 2 inches of hops in my primary. My gut and experience tells me that the hops might act as a "lid" or "cap" because of their density, which would cause the liquid below to absorb and suspend the CO2 more easily. It reminds me of a scenario; I make starters in 2L mason jars. If I put the lid on very tight and shake the hell out of the jar it makes a very small layer of foam, but the second I crack the lid open the foam expands all the way to the top of the jar in an instant. I would think that the hops in your fermenter are working the same way, and when you disturbed the hops it was like me cracking the lid on my mason jar.

Stauffbier said:

I can't answer this question with any sort of certainty or track record, as I've never had 2 inches of hops in my primary. My gut and experience tells me that the hops might act as a "lid" or "cap" because of their density, which would cause the liquid below to absorb and suspend the CO2 more easily. It reminds me of a scenario; I make starters in 2L mason jars. If I put the lid on very tight and shake the hell out of the jar it makes a very small layer of foam, but the second I crack the lid open the foam expands all the way to the top of the jar in an instant. I would think that the hops in your fermenter are working the same way, and when you disturbed the hops it was like me cracking the lid on my mason jar.

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That's what I would tend to believe as well. Hops have oils in them after all which would likely form a "skin" of sorts over the solution preventing any off-gassing until that lipid layer was disturbed. I'm not a chemist or anything remotely related so that's just an electrician/mechanic's semi-educated opinion